With the amperage involved and the caution "don't leave them on a flammable surface" that keeps coming up in forum posts(yes I used google), I was wondering if anyone had experience with them or could suggest another brand?

Is this what is being used when soldering sets of cells together, for those people making their own battery packs up?

Wikipedia has this to say (see below).

"LiPoly batteries must be charged carefully. The basic process is to charge at constant current until each cell reaches 4.2 V; the charger must then gradually reduce the charge current while holding the cell voltage at 4.2 V until the charge current has dropped to a small percentage of the initial charge rate, at which point the battery is considered 100% charged. Some manufacturers specify 2%, others 3%, but other values are also possible. The difference in achieved capacity is minute.

Balance charging simply means that the charger monitors the voltage of each cell in a pack and varies the charge on a per-cell basis so that all cells are brought to the same voltage."

Varies the charge on a per cell basis? I don't see how that's possible if they are soldered together.
Maybe do a batteries sticky

I get the feeling there's a great market out there for someone to sell a Lights-DIY-Forum-Approved charger and waterproofed batteries made from well-matched cells of 1S, 2S and 4S (3.7v, 7.4v and 14.8v), somewhere in North America.

K-Tronic has a solution, but its down-unda and hard to ship Lithium batteries by air.

It's a complicated area, and one that seems to handicap a lot of good light builds. Certainly scares off some of my friends.

Both lipo and li-ion cells need to be charge carefully to over charging and overdischarging to avoid going boom. That's why there are precautions. I charge all my packs outside, not that I am worried, I just don't want that one off failure burning down my house.

Lipo batteries are a gell style of battery, made up of several cells to achieve the output voltage, ie 3cell=11.1v 4 cell=14.8v etc. and are charged with a balance charger. Not many lipo's will have a battery protection circuit (PCB) hence the need for a good quality balance charger that will ensure that each cell only reaches a maximum of 4.2 volts (balance), at which time the charger will cut out. The cells are wired inseries to give teh output voltage but teh balance leads are wired to each individual cells +ve with a common -ve.

Li-ion ion look like a regular battery, have a harder case and usually have a built in PCB that monitors the voltage of the battery, cutting off charging at 4.2v and discharging at 3.3 or there abouts. The advantage of the Li-ion is that you can use a 4 cell pack for example with a smart charger or a regular balance charger but the use of a balance lead is not required as the PCB takes care of that.

I have a swallow brand balance charger that can handle almost any type of battery chemistry and will balance charge up to 6S. I also have a Tenergy 14.8v smart charger for my 14.8v 4S li-ion packs but my balance charger will also charge these but not with the balance lead.

Batteries are easy to waterproof if you plastidip them but you still need to ensure that the connectors are IP rated and if using a lipo that the balance lead is also waterproofed

Li-ion packs are more robust due to their hard case with lipo's being more fragile and easily punctured, unless you buy a hardcase RC car lipo.

But Li ion has the blance lead sorted out internally, making them appear like at high voltage standard AA type package?

Ah, you're getting slightly confused between a single cell and a pack (of cells). A LiPo pack (made up of a number of LiPo cells in series) will probably have an external balance lead to allow balancing of the individual cells within the pack. Each individual cell doesn't have a balance lead - it can't, as there's nothing to balance. You can do the same with a pack made up of Li-Ion cells in series, and have an external balance lead if you wish. LiPo and Li-Ion are simply slightly different chemistries but giving very similar results.

An individual Li-Ion cell can appear like a high-voltage AA cell (the 14500 Li-Ion is the same size as an AA) but there's no internal balance lead. The Li-Ion chemistry gives a nominal voltage of 3.7V (4.2V max charge) so a single Li-Ion cell is rated at 3.7V. There's nothing to balance within this - you can't divide it into two lots of 1.85V or anything else.

Generally people either use a charger to charge individual Li-Ion cells or they will use a charger to charge a pack of 2 or more cells together. If cells are being charged individually then there are no balance leads, but if cells are being charged as a pack then there may be balance leads for the charger to balance the cells properly.

For your own reference this is how the cells of a lipo pack are wired to the balance lead. http://www.wattflyer.com/forums/showthread.php?t=5467 Without a balance charger for a a lipo pack the cells will all be uneven in their voltage plus the risk is one cell could get more than 4.2 volts and be damaged.

As other here have said, lipo packs all have balance leads and I charge them with a balance charger. My li-ion packs have a PCB so I charge them with a smart charger without balance leads as the PCB ensures each cell gets the correct voltage.

The balance lead allows a number of cells connected together as a pack to be charged in parallel. While the discharge circuit is in series to create the higher voltage.
For the puck controller, being a constant current producing device.
Needed to drive the LED

So a balance charger is only needed when cells are wired into a pack.

Not allowing for any large blue drums of methanol, they are purely optional.

The balance lead allows a number of cells connected together as a pack to be charged in parallel. While the discharge circuit is in series to create the higher voltage.
For the puck controller, being a constant current producing device.
Needed to drive the LED

So a balance charger is only needed when cells are wired into a pack.

Not allowing for any large blue drums of methanol, they are purely optional.

Close! The cells in a pack will be connected in series or in parallel (or a combination) and nothing will change that - they are still connected that way during charging or discharging. A balance lead and balance charger is good if cells are wired into a pack in series, as it basically allows the individual voltages of the cells to be monitored and each cell charged fully (but not overcharged). If you didn't have the balance lead then theoretically over time some cells could be overcharged whilst others not receive a full charge (due to small differences in the cells' capacities).

You are right though - a balance charger is only needed when cells are wired into a pack. Indeed, if you take the cells out of the pack to charge them individually then you don't need a balance charger at all.

The PCB which brad72 links to is basically the clever bit of a balance charger (more or less), but fitted into the pack rather than as part of the charger. The balance leads are still there (note how the PCB has connections to the +ve and -ve of each cell) but all the cells, the connections and the PCB are integral within the pack, so the only connections on the outside of the pack are the overall +ve and -ve.

Not allowing for any large blue drums of methanol, they are purely optional.

Though my charging station post was made somewhat tongue in cheek, I do think there is a bit of hype over the "dangers" of LiIon cells. I've been using a mix of unprotected DX 18650 cheapies and salvaged laptop 18650s for 3 years now. One set in particular has been abused badly (over discharged twice) and they still work fine after "recharging". How many million LiIon cells are in use and what is the incident rate? One site I saw estimated 2-3 per million.

Though my charging station post was made somewhat tongue in cheek, I do think there is a bit of hype over the "dangers" of LiIon cells. I've been using a mix of unprotected DX 18650 cheapies and salvaged laptop 18650s for 3 years now. One set in particular has been abused badly (over discharged twice) and they still work fine after "recharging". How many million LiIon cells are in use and what is the incident rate? One site I saw estimated 2-3 per million.

I do know what you mean, Vancbiker. How many laptops are there in the world? How many mobile phones? They all use Li-Ion cells, as do a significant proportion of compact cameras now.

The balance lead allows a number of cells connected together as a pack to be charged in parallel. While the discharge circuit is in series to create the higher voltage.
For the puck controller, being a constant current producing device.
Needed to drive the LED

That is basically correct. The one clarification I would add is that some balance chargers really do change each cell individually (effectively in parallel), while some really charge the packs through the main connector (series connected) and just use the balance leads to shunt some of the charge current around the cells that are reaching full charge more quickly than the other cells. You can tell the type of charger by the connectors. A charger that only connects to the balance plug is charging the cells in parallel. A charger the connects to both the main connector and the balance connector is using the current shunt method.

Originally Posted by cam999

So a balance charger is only needed when cells are wired into a pack.

I would phrase it as balance charging only applies to a pack. "needed" is where you'll get into a big debate.

Most li-ion packs do not use balance charging because they have a protection PCB to detect and stop charge or discharge if any cell goes outside the acceptable voltage range. Most consumer pack with protection PCBs do not provide any true balance function, they just detect problems and shutdown the pack. These packs stay in balance because the cells are correctly matched. Some high end pack such as large capacity high end laptop packs, do have balance function included in the built in pack electronics. But they only provide very small balance currents and they are used sparingly to keep the pack perfectly tuned. If they detect that the packs are going significantly out of balance, they will shut it down just like less sophisticated protection PCBs.

li-po packs,which are used primarily in high current applications, typically do not have protection PCBs due to the high currents involved. They typically use balance chargers primarily as a way to monitor the voltages of each cell during charge since there is no protection PCB to monitor the voltage. Descent quality li-po packs rarely get out of actual balance. So it's more about monitoring the cell voltage to detect problems than actually getting the pack back into balance.

If you have a pack that's regularly going out of balance, then something is wrong with the pack and the root problem should be corrected. if you "get around" that issue by charging it with a balancing charger, then you're potentially increasing your risk of an issue. It's less dangerous than charging the same pack without a protection PCB or balance charger, but it's not a solution.

Good clarification, thanks MtbMacgyver. I haven't come across a charger working purely through the balance leads, only ones charging through the main leads and correcting with the balance leads - the current shunt method.

Though my charging station post was made somewhat tongue in cheek, I do think there is a bit of hype over the "dangers" of LiIon cells. I've been using a mix of unprotected DX 18650 cheapies and salvaged laptop 18650s for 3 years now. One set in particular has been abused badly (over discharged twice) and they still work fine after "recharging". How many million LiIon cells are in use and what is the incident rate? One site I saw estimated 2-3 per million.

If your point is the rate of problems is low enough that people shouldn't be afraid of using Li-ion battery technology, then I agree. But, the 2-3 per million is a statistic based on devices that use very good charge and discharge safety protections and practices. Most of those millions of batteries are in laptops, cell phones, and cameras that virtually all follow industry standard practices.

If your point is that they are safe enough that you don't need to worry about following the standard safety protection and practices, then I disagree. Let's say for the sake of discussion, that without standard safety practices the failure rate is 1 in 10k. That would still be what most people consider rare, and there would be plenty of folks that could say I've been doing that for years without an issue. But, since the standard practices are well understood and fairly easy and inexpensive, why wouldn't you?

If your point is the rate of problems is low enough that people shouldn't be afraid of using Li-ion battery technology, then I agree. But, the 2-3 per million is a statistic based on devices that use very good charge and discharge safety protections and practices. Most of those millions of batteries are in laptops, cell phones, and cameras that virtually all follow industry standard practices.

If your point is that they are safe enough that you don't need to worry about following the standard safety protection and practices, then I disagree. Let's say for the sake of discussion, that without standard safety practices the failure rate is 1 in 10k. That would still be what most people consider rare, and there would be plenty of folks that could say I've been doing that for years without an issue. But, since the standard practices are well understood and fairly easy and inexpensive, why wouldn't you?

My point was that used and charged properly they are safe and that in my experience they are not quite as sensitive to abuse as many think. I sense that many feel that the slightest deviation from standard best practices will result in fire, venting, or other incident.

My point was that used and charged properly they are safe and that in my experience they are not quite as sensitive to abuse as many think. I sense that many feel that the slightest deviation from standard best practices will result in fire, venting, or other incident.

I agree with that, there is no need for fear of li-ion batteries as being fundamentally unsafe. That would kinda be equivalent to being afraid of gasoline because it's extremely flammable.

I have to agree with the safety of of li-ion packs. The packs I charge outside are my unprotected lipo's, not because I do not have a good quality balance charger but because I have a mix of good quality rc batteries and cheap chinese ones. I got into the habit long ago with rc helicopter flying to charge the packs in the shed as although th odds of a fire or rupture are rare, they do happen so better to be safe than sorry.

Pretty much all lipo packs will have a balance lead (3-6 wires connected to a white socket) and 2 thick red and white power leads. They pretty much never come with a pcb because for RC hobbies the plane, car, or helicopter speed controller monitors the batteries voltage and shuts it down when voltage gets too low.

As for li-ion you just need to purchase ones that say they have a pcb fitted.

Simple answer is lipo packs without a protection PCB will usually have a balance charge connector as well as the main power connector. But the best way is to look at the specifications - it will say if it has a protection PCB or not.

1, A pack used for RC has no discharge protection. It's provided by the device.
2, If lipo packs are being used to drive LED lights these need to have protection for both charging and discharging, to make them work.

Go for the balance charger. I bought one a couple of years ago and have been very happy with it. I bought it to replace my single voltage Li-ion charger.

You just don't know what voltage or type of pack you might want to charge in the future so I think they are a good investment. Mine can also charge Life PO4 packs and these packs are getting more popular so this might come in handy in the future too.

For your own reference this is how the cells of a lipo pack are wired to the balance lead. http://www.wattflyer.com/forums/showthread.php?t=5467 Without a balance charger for a a lipo pack the cells will all be uneven in their voltage plus the risk is one cell could get more than 4.2 volts and be damaged.

As other here have said, lipo packs all have balance leads and I charge them with a balance charger. My li-ion packs have a PCB so I charge them with a smart charger without balance leads as the PCB ensures each cell gets the correct voltage.

Is there anywhere apart from battery space I can get this PCB?
Shipping is $78 they are quick, but thats still a lot of money for 100g or less

Batteryspace is famous for outrageous shipping charges.

If it's for a 14.8v, talk to Kerry at Ktronik for sure. He's making me a PCB with adapter to
turn an unprotected Lipo into a battery pack for my wife's light. Much better price too including shipping from Down Unda.

Incidentally, I also picked up a protected 4-cell holder for $16 including shipping on eBay.
See the Sticky on DIY parts.